class Solution {
    public int search(int[] nums, int target) {
        int left = 0;
        int right = nums.length - 1;
        while(left <= right) {
            //int mid = (left+right)/2;
            int mid = left + (right - left) / 2;//防溢出
            if(nums[mid] < target) {
                left = mid+1;
            }else if(nums[mid] > target) {
                right = mid-1;
            }else {
                return mid;
            }
        }
        return -1;
    }
}
/** 二段性
 * 朴素二分算法模版
 *           while(left <= right) {
 *             int mid = left + (right - left) / 2;//防溢出
 *             if(...) {
 *                 left = mid+1;
 *             }else if(...) {
 *                 right = mid-1;
 *             }else {
 *                 return ...;
 *             }
 *         }
 */